Present catheters or endoscopes are in the form of long tubes that are rigid or elastically deformable and that have an end that is steerable relative to a longitudinal axis of the tube so as to enable a particular viewing angle to be selected and so as to facilitate advancing the catheter or endoscope.
In order to curve a particular zone of the catheter or the endoscope appropriately, it is known to place actuators along its structure, which actuators are in the form of wires made of shape memory material, which wires are connected to Joule-effect heater means. Such actuators shrink in length under the effect of an increase in temperature thereby changing the curvature of the catheter or endoscope in the zones where the actuators are located. Controlling the various actuators distributed along the length of the endoscope or catheter enables its distal end to be positioned in three-dimensional space.
Nevertheless, that type of device presents several drawbacks. The diameter of the distal end is generally of the order of 5 millimeters (mm) to 8 mm so as to avoid bending under the effect of gravity. That excessive end diameter makes it impossible to investigate certain critical zones. In order to obtain the angular orientation desired for the end of the catheter or endoscope, it is necessary to modify parameters such as the length and the diameter of the actuator wires, and that is lengthy and complicated. Present devices also suffer from limitations due mainly to lack of mobility and maneuverability in places that are geometrically complex or cramped. During contraction of an actuator, bending locally gives the device a radius of curvature that is substantially constant since the stiffness of the device is substantially constant all along its length. Under such circumstances, it is not possible to inspect three-dimensional cavities of complex shape having passages of small dimensions and requiring a plurality of successive changes of orientation.
As a result, certain zones in a machine can remain inaccessible even though it is desired to perform conventional non-destructive inspection thereof, such as inspection performed using Foucault currents or ultrasound, given the complexity of access and of routing, and given the small dimensions of the passages to be followed. Finally, those known devices are not suitable for being controlled automatically, thereby correspondingly complicating the investigation procedure since it needs to be performed manually.